Story highlights

A frequently used Trump tactic is known among linguists as "paralipsis" ("to leave to the side")

It's a rhetorical technique that has its roots in Ancient Greece

(CNN)Cicero, Swift ... and Donald Trump?

The Republican nominee's campaign might be unprecedented, but a key element of his stump schtick is rooted in a rhetorical device pioneered by the Ancient Greeks.

For campaign watchers in 2016, the trope has become so familiar it typically slides by without notice. It is most commonly known among linguists as "paralipsis" ("to leave to the side"), a tool employed by the great Roman debater Cicero and Anglo-Irish satirist Jonathan Swift that allows a speaker to effectively say two things at once.

The pattern has played out repeatedly over the past 15 months of campaigning: Trump tells you he won't say something negative about a rival, and in so promising, does it anyway. He's used the device in talking about Bill and Hillary Clinton, a former Miss Universe, and past primary opponents including Carly Fiorina and Ben Carson, among others.

More than 80 million people heard it Monday night, in the closing minutes of Trump's first face-off with Hillary Clinton, when he told viewers that, despite plans to level an "extremely rough" charge against Clinton and her family, "I said to myself, I can't do it. I just can't do it. It's inappropriate."

Read More

A few minutes later, Trump turned it up a notch.

"I'm very happy that I was able to hold back on the indiscretions with respect to Bill Clinton," he told CNN's Dana Bash in the spin room as he raised the infidelity issue he'd skirted on stage, "because I have a lot of respect for Chelsea Clinton, and I just didn't want to say what I was going to say."

And there it was: Trump had not discussed the former president's extramarital affairs, except, of course, that he was quite obviously standing there, discussing the former president's extramarital affairs.

"Donald Trump uses paralipsis, repeatedly, and he does it in combination with another rhetorical figure, which is called argumentum ad baculum -- or threats of force," Dr. Jennifer Mercieca, an expert on political discourse at Texas A&M University, told CNN. "He implied that there was something that he was going to say, that he wanted to say, about Bill Clinton and infidelity, but that he wasn't."

"It was a threat," she said, "be nice to me or I'm going bring out these terrible things. And I think that's what we've seen from the surrogates, and from him, since the debates, so it keeps being lorded over the Clinton campaign's head -- that this thing is coming."

The device may be thousands of years old, but Trump has employed it in new and, at least in the modern American context, surprising ways.

"I've never seen anyone in public life use paralipsis the way he does," Mercieca said. "It's a clearly demagogic move. It allows him to recirculate information without being held accountable for it."

Such was the purpose during Trump's Wednesday night interview with Bill O'Reilly on Fox News, which followed more than a day of being questioned and criticized for his treatment of former Miss Universe Alicia Machado.

"So a lot of things are coming out about her," he said. "I'm not going to say anything."

Pressed to comment on whether Clinton had taken a "cheap shot" by bringing up Machado during the debate, Trump started in on the former beauty queen after vowing he wouldn't.

"A lot of things are coming out that I wasn't aware of, like they say that she threatened the life of a judge and got involved in all sorts of problems," he said.

During an August 2015 rally in New Hampshire, when Fiorina was enjoying a brief uptick in the GOP primary race, Trump observed that she had been "a little nasty" to him.

"So I promised that I wouldn't say, so I said it to myself, I promised I wouldn't say that she ran Hewlett-Packard into the ground," he said to hoots from supporters. "I said I will not say it -- that her stock value tanked. That she laid off tens of thousands of people and she got viciously fired. I said I will not say it."

And yet, he did.

Irony is implicit in paralipsis, which is why so many comedians use it to make us laugh and feel in on the joke.

A few months later, at a raucous rally in Fort Dodge, Iowa, Trump delivered a kind of oratorical masterclass.

First up was Marco Rubio:

"I will not call him a lightweight, because I think that's a derogatory term," Trump said. "So I will not call him a lightweight. Is that OK with you people? I refuse to say that he's a lightweight."

And then Ben Carson:

"Carson is an enigma to me," he said, prompting someone in the audience to yell, "Boring!' Without missing a beat, Trump replied, "I didn't say it!" Then he smiled and pointed into the crowd.

Asked months later by a Washington Post reporter if he would quietly concede in the event he lost a narrow race to Clinton, Trump once again found inspiration in Ancient Greece.

"I don't want to talk about that," he said as he then began talking about it. "I'm just saying that I wouldn't be surprised if the election ... there's a lot of dirty pool played at the election, meaning the election is rigged."